A053789 a(n) = A020639(A053790(n)).

2, 2, 2, 7, 2, 3, 2, 2, 2, 3, 2, 3, 2, 3, 2, 7, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 41, 2, 3, 2, 3, 2, 3, 2, 3, 2, 59, 2, 7, 2, 3, 2, 3, 2, 7, 2, 37, 2, 2, 5, 2, 2, 89, 2, 3, 2, 3, 2, 7, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 13, 2, 109, 2, 2, 17, 2, 2, 2, 7, 2, 7, 2, 2, 7, 2

Offset: 1

Author

Enoch Haga, Mar 27 2000

Keywords

• easy
• nonn

Examples

			a(4) = 7 because the sum of the first 8 primes is 77 and 7 is its least prime divisor.
		

Links

• Robert Israel, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A013918, A053790, A020639.

Programs

Maple

N:= 2000: # to use primes <= N
P:= select(isprime, [2, seq(i, i=3..N, 2)]):
A053790:= remove(isprime, ListTools:-PartialSums(P)):
map(t -> min(numtheory:-factorset(t)), A053790); # Robert Israel, Jan 29 2018

Extensions

Edited by N. J. A. Sloane, Mar 16 2008, following explication by R. J. Mathar, Feb 26 2008